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Violators will be prosecuted; Tue, 24 Apr 2018 05:42:07 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w3O4g6L48782162; Tue, 24 Apr 2018 04:42:06 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8564C52043; Tue, 24 Apr 2018 04:32:46 +0100 (BST) Received: from oc4502181600.in.ibm.com (unknown [9.124.35.76]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 9EB1D52045; Tue, 24 Apr 2018 04:32:44 +0100 (BST) From: Shilpasri G Bhat To: rjw@rjwysocki.net, viresh.kumar@linaro.org Cc: npiggin@gmail.com, benh@kernel.crashing.org, mpe@ellerman.id.au, linux-pm@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, ppaidipe@linux.vnet.ibm.com, svaidy@linux.vnet.ibm.com, Shilpasri G Bhat Subject: [PATCH] cpufreq: powernv: Fix the hardlockup by synchronus smp_call in timer interrupt Date: Tue, 24 Apr 2018 10:11:46 +0530 X-Mailer: git-send-email 1.8.3.1 X-TM-AS-GCONF: 00 x-cbid: 18042404-0044-0000-0000-0000054B69B2 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18042404-0045-0000-0000-0000288B9A90 Message-Id: <1524544906-31512-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-23_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804240045 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org gpstate_timer_handler() uses synchronous smp_call to set the pstate on the requested core. This causes the below hard lockup: [c000003fe566b320] [c0000000001d5340] smp_call_function_single+0x110/0x180 (unreliable) [c000003fe566b390] [c0000000001d55e0] smp_call_function_any+0x180/0x250 [c000003fe566b3f0] [c000000000acd3e8] gpstate_timer_handler+0x1e8/0x580 [c000003fe566b4a0] [c0000000001b46b0] call_timer_fn+0x50/0x1c0 [c000003fe566b520] [c0000000001b4958] expire_timers+0x138/0x1f0 [c000003fe566b590] [c0000000001b4bf8] run_timer_softirq+0x1e8/0x270 [c000003fe566b630] [c000000000d0d6c8] __do_softirq+0x158/0x3e4 [c000003fe566b710] [c000000000114be8] irq_exit+0xe8/0x120 [c000003fe566b730] [c000000000024d0c] timer_interrupt+0x9c/0xe0 [c000003fe566b760] [c000000000009014] decrementer_common+0x114/0x120 --- interrupt: 901 at doorbell_global_ipi+0x34/0x50 LR = arch_send_call_function_ipi_mask+0x120/0x130 [c000003fe566ba50] [c00000000004876c] arch_send_call_function_ipi_mask+0x4c/0x130 (unreliable) [c000003fe566ba90] [c0000000001d59f0] smp_call_function_many+0x340/0x450 [c000003fe566bb00] [c000000000075f18] pmdp_invalidate+0x98/0xe0 [c000003fe566bb30] [c0000000003a1120] change_huge_pmd+0xe0/0x270 [c000003fe566bba0] [c000000000349278] change_protection_range+0xb88/0xe40 [c000003fe566bcf0] [c0000000003496c0] mprotect_fixup+0x140/0x340 [c000003fe566bdb0] [c000000000349a74] SyS_mprotect+0x1b4/0x350 [c000003fe566be30] [c00000000000b184] system_call+0x58/0x6c Fix this by using the asynchronus smp_call in the timer interrupt handler. We don't have to wait in this handler until the pstates are changed on the core. This change will not have any impact on the global pstate ramp-down algorithm. Reported-by: Nicholas Piggin Reported-by: Pridhiviraj Paidipeddi Signed-off-by: Shilpasri G Bhat --- drivers/cpufreq/powernv-cpufreq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index 0591874..7e0c752 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -721,7 +721,7 @@ void gpstate_timer_handler(struct timer_list *t) spin_unlock(&gpstates->gpstate_lock); /* Timer may get migrated to a different cpu on cpu hot unplug */ - smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1); + smp_call_function_any(policy->cpus, set_pstate, &freq_data, 0); } /* -- 1.8.3.1